This invention relates generally to a magnetic detent arrangement and more particularly to an improved mechanism for assisting the magnetic detent arrangement and for providing tactile feedback to an operator.
In many hydraulic and pneumatic systems, control valves are provided for regulating the flow of fluid from a pressurized source to one or more control devices. Control devices are commonly used on machines to provide an input by an operator to perform desired functions on a work machine. Typically, the control devices are movable to a plurality of positions. The control devices are normally spring biased to return to a neutral position when the operator releases the control device. In many work machines, it is well known to provide a detent arrangement to hold the control device in a single position to reduce operator fatigue. There are many common types of detent arrangements that may be utilized for this purpose, including mechanical, magnetic, electromagnet and the like. Many of these detents have proven that they are not sufficient to hold the control device at the desired detented position when the machine is being subjected to rough terrain or the operator inadvertently touches the control device. Therefore, it is desirable to provide either a high force detent arrangement or a mechanism for assisting the detent arrangement that will more effectively hold the control device in the desired detented position. Likewise, it is desirable to provide a tactile feedback to the operator before the detent arrangement is engaged. Upon sensing the tactile feedback, the operator is able to avoid further movement of the control device and the resulting actuation of the detent arrangement. Also, in this manner, the operator will be aware of the location and xe2x80x9cfeelxe2x80x9d of the control device and the resulting function achieved on the work machine.
U.S. Pat. No. 6,098,481 issued on Aug. 8, 2000 to Rudy V. Mills, et al. discloses a high force detent mechanism that selectively holds a control input lever in any selected position between neutral and its maximum travel in either direction. The high force detent mechanism includes a coil assembly connected to a control input lever and disposed in close proximity to a semi-circular member having a serrated edge defined thereon. An armature of the coil assembly has as first portion in driving contact with the serrated edge and a second enlarged portion having a latching surface disposed adjacent one of the first and second end faces of the coil assembly""s detent coil. The size of the latching surface is larger than the size of the first portion that is in driving contact with the serrated edge. Consequently, the latching force generated between the latching surface and the one face of the detent coil is multiplied several times to create a detent holding force that is larger than the latching force. In this design, the detent holding force is created to increase the effective latching capability of the detent. Accordingly, an operator utilizing the detent mechanism would have to overcome the increased detent holding force in order to move the control lever to the neutral position. Due to the increased detent holding force, this effort may be fatiguing to the operator over extended periods of time. Also, the increased high force detent mechanism does not increase tactile feedback to the operator during movement of the control lever which is useful for assessing when a function of the work machine is changing.
U.S. Pat. No. 5,566,710 issued on Oct. 22, 1996 to Derek A. Dahlgren, et al. discloses an improved pre-detent tactile feedback assembly for a fluid control valve. The pre-detent tactile feedback assembly includes an elastic member, such as a garter type spring, seated within an annular groove formed in the bore of a plunger valve assembly. When the plunger is moved from an opened to a closed position, a portion of the plunger contacts the elastic member, urging the elastic member outwardly into the groove. The additional force required to urge the elastic member into the groove provides a xe2x80x9cfeelxe2x80x9d force to the control lever. Preferably, the groove is positioned within the bore so that this feelxe2x80x9d force is sensed just prior to actuation of an associated detent assembly. In this design, the improved structure effectively increases the force required to move the control lever just prior to engagement of the detent but does not increase the force acting against the detent to assist in holding the detent in a desired detented position.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, a detent assist assembly for a detent arrangement comprises a first member with an outer surface that includes a resistance portion. A second member is movable from a neutral position to first and second positions wherein movement to the first position engages the second member with the resistance portion and movement to the second position disengages the second member from the resistance portion. The second member is operative with the resistance portion when in the second position to assist in holding the detent arrangement in a predetermined position.
In another aspect of the present invention, a control arrangement is disclosed for actuating at least two control valves. The control arrangement comprises a control device that is movable from a neutral position to first and second control positions. The control device has an actuator for actuating one of the control valves when moved to the first control position. A detent arrangement is operative with the control device for holding the control device in the first control position. A detent assist assembly is operative with the control device with means for assisting the detent arrangement in holding the control device in the first control position. The detent assist assembly has an actuator for actuating the other one of the control valves when the control device is moved to the second control position.
The present invention is a control arrangement that includes a detent assist assembly for assisting a detent arrangement in holding a control device in a predetermined position. Additionally, the detent assist assembly serves as an actuator for a control valve operative with the control device. Further, the detent assist assembly provides tactile feedback to an operator through the control device. The present invention is a simple and efficient device for providing the improved features herein.